var app = function () {
  var init = function(exports) {

    // 修改父类基础函数
    this.fn.bindListener = function() {
      console.log('this is help children bindListener');
    };

    // 其他函数依旧继承父类
    this.fn.init(exports);
    console.log('hello help');
  };
  this.init = init;
  return this;
}
module.exports = app;